A Dodge Stealth is driving at 70 mph on a highway. It passes a BMW going the same direction. The BMW is moving 7 mph backward relative the Dodge. 63 mph is the velocity of the BMW
Answer: Option A
Explanation:
Given is the speed of the dodge stealth as 70 mph passing by the BMW moving with 7 mph relative to Dodge. Thereby, to calculate the velocity of BMW, relative velocity concept has to be employed. Â
As we know that the relative velocity tells us about relative velocity of mobile reference system as the difference or sum of the initial reference system.
Therefore,
velocity of the BMW = Â [tex]v_{b}[/tex]
Velocity of the dodge = [tex]v_{d}[/tex]
Velocity of the BMW with respect to dodge = [tex]V_{b d}[/tex]
As per the formula,
           [tex]v_{b d}=v_{b}-v_{d}[/tex]
    [tex]v_{b} = v_{d} + v_{b d} = 70 + (-7) = 70 - 7 = 63 \mathrm{mph}[/tex]
